Temperature control device and method of manufacturing the same

ABSTRACT

A temperature control device includes a heat pipe including a heat absorption part provided at one end side and absorbing heat from an outside and a heat dissipation part provided at another end side and dissipating heat to the outside, and a heat absorption plate and a heat dissipation plate (heat conducting plates) made of metal films formed by powder including metal being accelerated with a gas toward at least one of external surfaces of the heat absorption part and the heat dissipation part of the heat pipe and being sprayed and deposited on the surfaces in a solid-phase state.

FIELD

The present invention relates to a temperature control device usedbetween electrical circuit boards and the like and a method ofmanufacturing the same.

BACKGROUND

Conventionally, a temperature control device (a cooling device or aheating device) that distributes or circulates a heating medium, whichcools or heats a surface of a board, has been used, in various boardprocesses in manufacturing a semiconductor, a liquid crystal displaydevice, an optical disk, and the like. Such a temperature control deviceis produced, for example, by disposing and allowing a heat pipe to be incontact with an upper side and/or a lower side of the board. Since theheat pipe has a good heat transfer property, the heat pipe canefficiently transfer heat of the heating medium from the board to anoutside or from the outside to the board, and can promptly control aboard temperature.

The heat pipe has a cylindrical shape that forms an inner space, bothends of which are closed in a vacuum state. The heat pipe includes aheat absorption part provided at one end side and absorbing heat fromthe outside, and a heat dissipation part provided at another end sideand dissipating heat to the outside. Further, a capillary structure,called a wick, is formed on a wall surface of the inner space of theheat pipe, and a liquid (for example, water and a small amount ofalcohol) is enclosed.

In the heat pipe, when heat is applied from the outside to the heatabsorption part, the liquid enclosed inside is evaporated, and vapor ismoved to the heat dissipation part. At this time, since the inner spaceof the heat pipe is in a vacuum state, the liquid is vaporized at orless than a boiling temperature under ordinary pressure. The vapor movedto the heat dissipation part returns to a liquid again, and moves to theheat absorption part by capillary phenomenon of the wick. As describedabove, in the heat pipe, the liquid enclosed inside repeats evaporationand condensation between the heat absorption part and the heatdissipation part, so that prompt heat transfer is performed.

Further, the heat absorption part and the heat dissipation part of theheat pipe improve the efficiency of heat absorption and heat dissipationby being joined with heat conducting plates. Here, in the heatconducting plate, the heat absorption part is joined to a heatabsorption plate, for example. This heat absorption plate allows theheat absorption part to transfer heat generated by the board and thelike arranged at other positions on the heat absorption plate. Also, theheat dissipation part is joined to a heat dissipation plate, anddissipates the heat transferred from the heat absorption part to theheat dissipation part to the outside through the heat dissipation plate.

Conventionally, a heat pipe joined to a heat conducting plate by solderhas been known, the heat conducting plate having a board as an object tobe temperature-controlled disposed thereon (for example, see PatentLiterature 1). Further, a heat pipe type cooler that suppresses effectsof heat in solder joint is disclosed, in which an insertion hole isformed in a plate to which a heat pipe is disposed, and one end portionof the heat pipe is inserted to the insertion hole and the heat pipe andthe plate are connected (for example, see Patent Literature 2).

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Application Laid-open No.    6-181396-   Patent Literature 2: Japanese Patent Application Laid-open No.    7-142653

SUMMARY Technical Problem

However, in the joint by solder disclosed in Patent Literature 1,although the strength of the joint between the heat conducting plate andthe heat pipe can be secured, the heat pipe may be damaged by heatapplied at the time of the solder joint. Further, peeling and cracks areeasily caused in the formation of solder, and the formation is coarsenedwhen being held under a high-temperature environment for a long time, sothat the strength is lowered. Therefore, there is a problem thatreliability of the joint strength between the heat pipe and the heatabsorption part (heat dissipation part) is low.

Further, in the heat pipe type cooler disclosed in Patent Literature 2,the heat pipe is not damaged by heat. However, it is structured suchthat the heat pipe is inserted to the insertion hole, and therefore,there is a problem that the joint strength between the heat pipe and theheat conducting plate is low. Due to such a problem, heat resistancebetween the heat pipe and the heat absorption part (heat dissipationpart) becomes higher, and excellent heat transport ability of the heatpipe cannot be utilized.

The present invention has been made in view of the foregoing, and anobjective of the present invention is to provide a temperature controldevice and a method of manufacturing the temperature control devicecapable of joining a heat conducting plate and a heat pipe with highjoint strength without damaging the heat pipe by heat.

Solution to Problem

To solve the problem described above and achieve the object, atemperature control device according to the present invention includes:a heat pipe including a heat absorption part provided at one end sideand absorbing heat from an outside and a heat dissipation part providedat another end side and dissipating heat to the outside, and adapted tocontrol a temperature of an object to be temperature-controlled; and ametal film formed by powder including metal being accelerated with a gastoward external surfaces of the heat absorption part and/or the heatdissipation part, and being sprayed and deposited on the surfaces in asolid-phase state.

Moreover, in the temperature control device described above, a part ofthe external surface of the heat absorption part of the heat pipe is incontact with the object to be temperature-controlled, and the externalsurface other than a contact part is covered with the metal film.

Moreover, in the temperature control device described above, the metalused for the metal film includes at least one kind selected from a groupconsisting of copper, molybdenum, aluminum, tungsten, silver, nickel,titanium, and a stainless based alloy or an alloy including at least oneof copper, molybdenum, aluminum, tungsten, silver, nickel, and titanium.

Moreover, a method of manufacturing a temperature control deviceaccording to the present invention is a method of manufacturing atemperature control device including a heat pipe adapted to control atemperature of an object to be temperature-controlled, and the methodincludes: a step of forming a metal film by accelerating powderincluding metal with a gas toward a surface of at least one end portionof the heat pipe and by spraying and depositing the powder on thesurface in a solid-phase state.

Moreover, the method of manufacturing a temperature control devicedescribed above further includes a step of holding the heat pipe by ajig holding a part of the surface of the end portion of the heat pipe,and wherein the step of forming a metal film includes a first step offorming the metal film by accelerating powder including metal with a gastoward a surface exposed outside and of the heat pipe held by the jig inthe step of holding the heat pipe, and by spraying and depositing thepowder on the surface in a solid-phase state, and a second step offorming the metal film by removing the jig after the first step offorming the metal film, by accelerating powder including metal with agas toward a surface of the heat pipe, having exposed outside, and byspraying and depositing the powder on the surface in a solid-phasestate.

Advantageous Effects of Invention

The temperature control device and the method of manufacturing thetemperature control device according to the present invention joins endportions of a heat pipe and heat conducting plates with films formed bya cold spray method. Therefore, there is an effect of joining the heatconducting plates and the heat pipe with high joint strength withoutdamaging the heat pipe by heat.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view schematically illustrating a configurationof a temperature control device according to an embodiment of thepresent invention.

FIG. 2 is a schematic diagram illustrating an outline of a cold sprayapparatus used for manufacturing the temperature control deviceaccording to the embodiment of the present invention.

FIG. 3 is a cross sectional view describing formation of a heatdissipation plate of the temperature control device according to theembodiment of the present invention.

FIG. 4 is a cross sectional view describing formation of the heatdissipation plate of the temperature control device according to theembodiment of the present invention.

FIG. 5 is a cross sectional view describing formation of the heatdissipation plate of the temperature control device according to theembodiment of the present invention.

FIG. 6 is a cross sectional view describing formation of the heatdissipation plate of the temperature control device according to theembodiment of the present invention.

FIG. 7 is a cross sectional view describing formation of the heatdissipation plate of the temperature control device according to theembodiment of the present invention.

FIG. 8 is a cross sectional view illustrating a configuration of aprincipal part of a temperature control device according to a firstmodification of the embodiment of the present invention.

FIG. 9 is a cross sectional view illustrating a configuration of aprincipal part of a temperature control device according to a secondmodification of the embodiment of the present invention.

FIG. 10 is a cross sectional view illustrating a configuration of aprincipal part of a temperature control device according to a thirdmodification of the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment for implementing the present invention willbe described in detail with reference to the drawings. Note that thepresent invention is not limited by the embodiment below. Further, thedrawings referenced by the description below merely illustrate theshape, the size, and the positional relationship in a schematic mannerto the extent that the content of the present invention can beunderstood. That is, the present invention is not limited by the shape,the size, and the positional relationship exemplarily illustrated in thedrawings.

First, a temperature control device according to an embodiment of thepresent invention will be described in detail with reference to thedrawings. Note that, in the description below, a temperature controldevice that cools a board, which incorporates a semiconductor device,will be described as an example of a temperature control device. FIG. 1is a perspective view schematically illustrating a configuration of thetemperature control device according to the embodiment of the presentinvention. A temperature control device 1 illustrated in FIG. 1 includesa board 11 that incorporates a chip 10 realized by a semiconductordevice, such as a diode, a transistor, and an insulated gate bipolartransistor (IGBT), and a heat pipe 12 that cools the board 11.

A circuit pattern (not illustrated) for transferring an electricalsignal to the chip 10, which is incorporated in the board 11, is formedon a surface of the board 11, which is not joined to the heat pipe 12.This circuit pattern is formed by patterning using metal, such ascopper. Note that a plurality of chips 10 is provided on the board 11according to a purpose of use.

The heat pipe 12 includes a heat absorption plate 13 joined to the board11 and holding one end of the heat pipe 12, and a heat dissipation plate14 formed at an end portion of the heat pipe 12 on a different side fromthe side connected with the board 11. Further, the heat pipe 12 includesa heat absorption part 12 a provided in an end portion on the board 11side, and a heat dissipation part 12 b provided in an end portion on thedifferent side from the board 11 side.

The heat absorption plate 13 and the heat dissipation plate 14 as heatconducting plates are metal films formed on surfaces of the heatabsorption part 12 a and of the heat dissipation part 12 b of the heatpipe 12 by a cold spray method described below. Examples of the metalfilms include copper, molybdenum, aluminum, tungsten, silver, nickel,titanium, and a stainless based alloy or an alloy including at least oneof copper, molybdenum, aluminum, tungsten, silver, nickel, and titanium.With the metal films, heat generated from the chip 10 can be efficientlyabsorbed by the heat absorption part 12 a through the board 11, and theheat conducted to the heat dissipation part 12 b can be efficientlydissipated to an outside. Here, as the metal films, any metal or alloyhaving the density of 95% or more and the heat conductivity of 90% ormore with respect to a bulk material of the same kind is applicable.

Next, formation of the heat absorption plate 13 (metal film) of the heatabsorption part 12 a will be described with reference to FIG. 2. FIG. 2is a schematic diagram illustrating an outline of a cold spray apparatusused for the formation of the metal film. A cold spray apparatus 20includes a gas heater 21 that heats a compressed gas, a powder supplydevice 22 that houses a powder material thermally sprayed onto an objectto be sprayed and supplies the powder material to a spray gun 24, and agas nozzle 23 that thermally sprays material powder mixed with theheated compressed gas onto a base material with the spray gun 24.

Examples of the compressed gas include helium, nitrogen, and air. Thesupplied compressed gas is supplied to the gas heater 21 and to thepowder supply device 22 by valves 25 and 26, respectively. Thecompressed gas supplied to the gas heater 21 is heated to about 50 to700° C., and is then supplied to the spray gun 24. More favorably, thecompressed gas is heated such that an upper limit temperature of thepowder thermally sprayed onto the board 11 is kept equal to or less thana melting point of the metal material. This is because, by keeping theheating temperature of the powder material to be equal to or less thanthe melting point of the metal material, oxidation of the metal materialcan be suppressed.

The compressed gas supplied to the powder supply device 22 is suppliedsuch that the material powder having a particle diameter of about 10 to100 μm in the powder supply device 22 is supplied to the spray gun 24 ata predetermined discharge rate. The heated compressed gas is caused tobe a supersonic flow (about 340 m/s or more) with the gas nozzle 23having a convergent divergent shape. The powder material supplied to thespray gun 24 is accelerated by being thrown into the supersonic flow ofthe compressed gas, and collides with the base material in a solid-phasestate to form a film.

A metal film (heat absorption plate 13) as illustrated in FIG. 1 isformed by the above-described cold spray apparatus 20. Note that thecold spray apparatus is not limited to the cold spray apparatus 20 ofFIG. 2 as long as one can form a film by allowing the material powder tocollide with the base material in a solid-phase state. Further, it hasbeen described in the present embodiment that the heat pipe 12 is incontact with the board 11. However, the metal film 13 may lie betweenthe board 11 and the heat pipe 12. Such a configuration is applicable aslong as it can transfer the heat generated by the board 11 to the heatabsorption part 12 a of the heat pipe 12.

Next, formation of the heat dissipation plate 14 (metal film) of theheat dissipation part 12 b will be described with reference to FIGS. 3to 7. FIGS. 3 to 7 are cross sectional views describing the formation ofthe heat dissipation plate according to the embodiment. First, asillustrated in FIG. 3, a metal film 14 a is formed so as to cover anexternal surface of the heat pipe 12 using the cold spray apparatus 20illustrated in FIG. 2 with respect to the heat pipe 12 (heat dissipationpart 12 b) held by a jig 30. Here, the jig 30 has a recess portion thatholds a part of the surface of an end portion of the heat pipe 12.

As illustrated in FIG. 3, after one external periphery of the heat pipe12 is covered with the metal film, a film formation (see FIG. 4) formedby the metal film 14 a being layered is inverted with respect to thecold spray apparatus 20, and the jig 30 is removed (FIG. 5). Followingthat, a metal film 14 b is formed on the external surface of the heatpipe 12 that had been covered by the jig 30 (FIGS. 6 and 7). Here, thejig 30 is formed using a material having a coefficient of linear thermalexpansion substantially different from that of the metal used for theheat dissipation plate 14 to be formed. Consequently, the jig 30 can beeasily removed from the heat pipe 12.

By the above-described processing, the external surface of the heat pipe12 (heat dissipation part 12 b) is covered with the metal films 14 a and14 b, as illustrated in FIG. 7, and the heat dissipation plate 14 can beformed. Note that, in forming a film, in a case where a metal film alonga surface shape formed by the jig 30 and the heat pipe 12 is formed, theshape of the surface can be controlled by applying surface finishingprocessing, such as machining.

According to the temperature control device of the above-describedembodiment, the end portion of the heat pipe is covered with the metalfilm formed by the cold spray method. Therefore, the heat pipe is notdamaged by heat, and the board and the heat pipe can be joined with highjoint strength. Consequently, the limitation of a working temperatureand an amount of heat transport caused in a past temperature controldevice made by solders and the like under a low melting point can beimproved while the durability of the temperature control device can beenhanced.

Further, the cold spray method can form a more precise metal film than athermal spray method that performs high-temperature processing.Therefore, the metal characteristic of the metal film formed by the coldspray method is superior to that of a metal film formed by the thermalspray method, and the like. Consequently, the heat conductivity of themetal film is improved, and more efficient heat conduction can berealized between the heat pipe and the heat absorption part (heatdissipation part). For example, a copper film by the cold spray methodhas the density of 95% or more than a copper bulk material. Also, in thecold spray method, the powder is heated only to the degree that thesolid-phase state of the metal powder can be maintained, and theoxidation of the powder is suppressed. Therefore, the heat conductivityhas a characteristic of 90% or more than the bulk material.

Note that the metal film has been described as a cooling fin thatreleases the heat generated from the chip. However, the metal film canbe provided to heat the board and the like through the metal film.

Further, the metal film-forming region by the cold spray method is aregion where a heated portion and the heat pipe are at least connectedand where the joint may just be reliably performed, regardless ofuniformity of the shape of the metal film.

Further, the heat pipe 12 has been described to have a U shape. However,any shape in a bent manner or in a linear manner other than the U shapemay be employed.

FIG. 8 is a schematic diagram illustrating a configuration of aprincipal part of a temperature control device according to a firstmodification of the embodiment. As illustrated in FIG. 8, in a casewhere the heat pipe 12 is arranged adjacent to a base plate 31, on whicha board and the like that are objects to be temperature-controlled areplaced, a metal film 14 c is formed on an surface on which the heat pipe12 is arranged by a cold spray method.

Note that the base plate 31 may be a heat conducting sheet made of aheat absorption sheet or a heat dissipation sheet.

FIG. 9 is a schematic diagram illustrating a configuration of aprincipal part of a temperature control device according to a secondmodification of the embodiment. As illustrated in FIG. 9, a heat pipe 15may have a cross section of an approximately rectangular shape. In thiscase, in a heat dissipation part, similarly to FIG. 7, a heatdissipation plate 16 is formed by forming metal films 16 a and 16 busing a jig. A surface of a heat pipe, which has a larger area, iscaused to face a board, so that the area facing the board can beenlarged and efficiency of the heat transfer can be improved.

Further, FIG. 10 is a schematic diagram illustrating a configuration ofa principal part of a temperature control device according to a thirdmodification of the embodiment. As illustrated in FIG. 10, the heat pipe15 having an approximately rectangular cross section may be held by ajig 30 a that surrounds and holds three surfaces of the heat pipe 15. Inthis case, in a heat dissipation part, similarly to FIGS. 3 to 7, aftera metal film 17 a is formed using the jig, the metal film 17 a isinverted and the jig 30 a is removed, and a film is formed, so that aheat dissipation plate can be produced.

According to the third modification, a surface on which the metal filmis formed by a cold spray method in the first process is flat. Thus,after the film is formed, surface finishing processing such as machiningis not required for the surface, and therefore, the working process canbe reduced.

INDUSTRIAL APPLICABILITY

As described above, the temperature control device and the method ofmanufacturing the same according to the present invention prevent theheat pipe from heat damage, and are useful when the board or the metalfilm and the heat pipe are joined with high joint strength.

REFERENCE SIGNS LIST

-   -   1 Temperature control device    -   10 Chip    -   11 Board    -   12 and 15 Heat pipe    -   12 a Heat absorption part    -   12 b Heat dissipation part    -   13 Heat absorption plate    -   14 Heat dissipation plate    -   20 Cold spray apparatus    -   21 Gas heater    -   22 Powder supply device    -   23 Gas nozzle    -   24 Spray gun    -   25 and 26 Valve

1. A temperature control device comprising: a heat pipe including a heatabsorption part provided at one end side and absorbing heat from anoutside and a heat dissipation part provided at another end side anddissipating heat to the outside, and adapted to control a temperature ofan object to be temperature-controlled; and a metal film formed bypowder including metal being accelerated with a gas toward at least oneof external surfaces of the heat absorption part and the heatdissipation part, and being sprayed and deposited on the surfaces in asolid-phase state.
 2. The temperature control device according to claim1, wherein a part of the external surface of the heat absorption part ofthe heat pipe is in contact with the object to betemperature-controlled, and the external surface other than a contactpart is covered with the metal film.
 3. The temperature control deviceaccording to claim 1, wherein the metal used for the metal film includesat least one kind selected from a group consisting of copper,molybdenum, aluminum, tungsten, silver, nickel, titanium, and astainless based alloy or an alloy including at least one of copper,molybdenum, aluminum, tungsten, silver, nickel, and titanium.
 4. Amethod of manufacturing a temperature control device including a heatpipe adapted to control a temperature of an object to betemperature-controlled, the method comprising: a step of forming a metalfilm by accelerating powder including metal with a gas toward a surfaceof at least one end portion of the heat pipe and by spraying anddepositing the powder on the surface in a solid-phase state.
 5. Themethod of manufacturing a temperature control device according to claim4, further comprising: a step of holding the heat pipe by a jig holdinga part of the surface of the end portion of the heat pipe, and whereinthe step of forming a metal film includes a first step of forming themetal film by accelerating powder including metal with a gas toward asurface exposed outside and of the heat pipe held by the jig in the stepof holding the heat pipe, and by spraying and depositing the powder onthe surface in a solid-phase state, and a second step of forming themetal film by removing the jig after the first step of forming the metalfilm, by accelerating powder including metal with a gas toward a surfaceof the heat pipe, having exposed outside, and by spraying and depositingthe powder on the surface in a solid-phase state.
 6. The temperaturecontrol device according to claim 2, wherein the metal used for themetal film includes at least one kind selected from a group consistingof copper, molybdenum, aluminum, tungsten, silver, nickel, titanium, anda stainless based alloy or an alloy including at least one of copper,molybdenum, aluminum, tungsten, silver, nickel, and titanium.